Hspice simulation of cascaded transmission line [unstable?]

Hey, folks:

I am simulating a system of several cascaded transmission lines.

Hspice will give me very unstable waveform, while eldo is still very stable for same circuit. Which simulator should I trust?

For circuit view, I do not think that circuit should be unstable. How to make hspice give me right waveform?

thanks,

<<Gear option already used and doesn't help.>>

In general, the spice matrix solution does't like high impedance nodes with no path to ground. For instance, two capacitors in series may not converge. I don't know how the component is made in hspice but you might try large resistors (multi megohm) to ground at the point where the transmission lines connect together. That should not affect your results but may help it converge.

I've used option gshunt=1e-5.
The situation doesn't change. Headache...